in the environment, many things mix or dissolve in water
water can be polluted by
insoluble substances, such as oil, plastics, tyres, tins, glass, toilet waste
soluble substances such as soaps, fertilizers, insecticides, acids and other poisons
living germs from toilet waste causing water-borne illnesses such as diarrhoea
Teacher Input 1
Greet the learners.
Remind them that in their previous lessons, they learnt about dissolving. Ask learners if they can explain what happens when something dissolves.
Answer: Dissolving involves two substances – a solute and a solvent. The resulting solution is a mixture of both. The dissolved substance is still present in the solution even though it cannot be seen.
Remind learners that they have also learnt about soluble and insoluble substances. What is the difference between these two?
Answer: Soluble substances are those that easily dissolve in a solvent, such as water, and include sugar, salt, alcohol and some dishwashing detergents.
Insoluble substances are substances that do not dissolve in a solvent (e.g. chalk is insoluble in water).
Tell learners that in this lesson they are going to learn how soluble and insoluble substances can be bad for the environment and pollute our water.